Our EP-B-1032531 discloses a container for foodstuff formed from a one piece blank of card and having isosceles triangular shaped end walls connected by quadrilateral side walls to form a triangular prism shaped container, one side wall of the container being hinged along the base of one of the end walls to provide a lid for the container, with a window in the lid to permit the contents of the container to be viewed. Blanks for forming the containers are preformed with fold lines and windows. Selected walls of the blanks have tabs which are glued to the inside faces of adjacent walls to form prism shaped containers. Fold lines are formed in the triangular walls of the container and lid to enable the container to be folded flat.
Our UK-A-2397573 discloses a carton for a diagonally cut sandwich or like foodstuff formed from a blank of card and having triangular end walls connected by quadrilateral side walls to form a triangular prism-shaped container. One side wall of the container is hinged to one of the end walls of the container to provide an opening for insertion/removal of foodstuff and to form a lid for closing the opening. The edges of the opening have out-turned flanges, and the periphery of the lid overlies the out-turned flanges encircling the opening when the lid is in the closed position whereby the lid can be bonded to the flanges to seal the contents of the carton.